1. Field of the Invention
The present invention relates a driving circuit for a vibration type actuator and mounting of the driving circuit.
2. Related Background Art
Conventionally, as an oscillating means forming a driving circuit for a vibration type actuator, a means using a VCO or a means for frequency-dividing an high-frequency pulse signal and outputting the resultant signal has been used.
Since the frequency of such an analog oscillating means has a high temperature dependency, when the oscillating means is integrated with a power amplification means, the frequency precision decreases. A VCO using a quartz oscillator suffers a narrow frequency setting range. In addition, when frequencies are to be set by digitally dividing the frequency of the quartz oscillator, the resolution of the resultant frequencies is low. Such frequencies are unsuited to control the speed of a vibration type actuator.
Furthermore, a conventional driving circuit for a vibration type actuator is comprised of a combination of discrete electronic parts, and different parts are connected and used as a power amplification means, a CPU for controlling the operation of the vibration type actuator, an oscillating means, and the like.
Since a plurality discrete parts are used, a circuit board requires a large mounting area. In addition, since it takes much time to mount the parts on the circuit board, the manufacturing cost of the circuit board increases. Under the circumstances, the respective parts may be integrally mounted. As described above, however, since the frequency of the analog oscillating means has a high temperature dependency, if the oscillating means and the power amplification means are integrated, the frequency precision decreases. In addition, the VCO using the quartz oscillator suffers a narrow frequency setting range. It is therefore difficult to integrally mount these parts. Furthermore, if a circuit for setting frequencies by digitally dividing the frequency of a quartz oscillator is used, the problem of the temperature dependency can be solved. However, in a circuit using such a method, the resolution of frequencies is low, and hence this circuit is unsuited to control the speed of the vibration type actuator.